Liquid cooling arrangement for dynamoelectric machine

ABSTRACT

A method of and apparatus for cooling the heat-producing electrical windings of a dynamoelectric machine by spraying them directly with atomized coolant to deposit a coating of liquid coolant which flows over and away from them to carry away heat picked up from them by conduction. Hydraulically atomized particles are projected at low velocity to thoroughly wet or coat the structures to be cooled and to increase the heat transfer to the coolant. The spray nozzles are arranged and their outputs shielded to minimize any insulation erosion that might result from centrifugal motion of coolant and from the low velocity sprays.

United States Patent FUJI! Mar. 7, 1972 [54] LIQUID COOLING ARRANGEMENTFOR DYNAMOELECTRIC MACHINE [72] Inventor: Robert L. Fujii, Cleveland,Ohio [73] Assignee: Lear Siegler, Inc., Santa Monica, Calif.

[22] Filed: Mar. 26, 1970 [21] Appl. No.2 22,752

[52] US. Cl ..310/54 [51] Int. Cl. .....H02k 9/20 [58] Field ofSearch..3l0/54,55,58,59,64, 159, 310/168, 171

[56] References Cited UNITED STATES PATENTS 3,030,529 4/1962 .laeschke..310/54 3,445,695 5/1969 Schultz ..310/58 3,479,541 11/1969 Robinson.3,480,810 11/1969 Potter ..310/54 Primary Examiner-William M. Shoop,.lr. Assistant Examiner-R. Skudy Attorney-Bosworth, Sessions, Herrstromand Cain [57] ABSTRACT A method of and apparatus for cooling theheat-producing electrical windings of a dynamoelectric machine byspraying them directly with atomized coolant to deposit a coating ofliquid coolant which flows over and away from them to carry away heatpicked up from them by conduction. Hydraulically atomized particles areprojected at low, velocity to thoroughly wet or coat the structures tobe cooled and to increase the heat transfer to the coolant. The spraynozzles are arranged and their outputs shielded to minimize anyinsulation erosion that might result from centrifugal motion of coolantand from p the low velocity sprays.

12 Claims, 3 Drawing Figures Patented March 7, 1972 3,648,085

5 Sheets-Sheet l INVENTOR.

205592 4. FUJI! Patented March 7, 1972 3 Sheets-Sheet 2 INVENTOR.

QOfi'EfiT A. FUJI] Patented March 7, 1972 3,648,085

5 Sheets-Sheet 5 INVENTOR.

05627 4. FUJI] LIQUID COOLING ARRANGEMENT FOR DYNAMOELECTRIC MACHINEBACKGROUND OF THE INVENTION In aircraft and in other applications whereweight is a penalty, dynamoelectric machines having high ratios ofoutput per unit of weight are highly desirable. Various factorscontribute to the achievement of this objective, including improvementsin materials and higher operating speeds. Another route to increasedweight reduction and better reliability is through improved cooling ofthe electrical windings. Improved cooling permits a reduction in bothcopper and supporting structure weight by permitting the use ofincreased current densities while maintaining winding temperatureswithin accepted thermal limits.

Known methods of cooling dynamoelectric machines include air cooling.Such machines have relatively open construction and provide efficientcooling to the extent permitted by the specific heat value of airbecause the cooling medium or air is in intimate contact with theheat-producing windings and core sections.

Oil is preferred to air as a cooling medium because it has a higherspecific heat value. In conventional oil-cooled machines, however, ithas generally been accepted as desirable to contain the cooling oilwithin closed ducts or passages routed in close proximity to theheat-producing parts of the machine. The success of such coolingarrangements depends upon short thermal paths and the reduction of highthermal gradients between the hot windings and the cooling oil. It alsousually requires sometimes troublesome rubbing seals. Unfortunately, thesteps often necessary to accomplish this successfully tend to increasethe weight of the machine, and reduce reliability.

Recently, direct oil cooling schemes combining the direct contactapproach of air cooling with the high specific heat value of oil as acooling medium have been employed. Basically, these schemes haveinvolved simply jetting cooling oil from a hollow rotor shaft, forexample, into the interior of the machine. By the use of deflectors ormerely by suitable location of the jets, the flow of coolant oil isattempted to be directed at the hot windings and end turns of theshaftmounted rotating element. The stationary windings and structurerely upon coolant being thrown onto them by centrifugal force. Directoil cooling by jet tends to permit increases in the allowable currentdensity over air-cooled and sealed oil cooling systems. The methodsuffers from an inability to intimately contact all the normally exposedsurface areas of the hot windings and core structures. Also, deleteriouserosion of the insulation on the exposed windings often results from theimpingement of the oil jet on the windings and from centrifugalimpingement of oil flung from the rotating parts. Finally, quantities ofunatomized liquid oil resulting in jet cooling systems and,particularly, the liquid oil invariably present in the airgap betweenthe stationary and rotating elements produces windage and churninglosses which tend to offset advantages obtained from the heat transfercharacteristics of such jet cooling.

BRIEF SUMMARY OF THE INVENTION This invention relates to an improvedmethod and means for oil spray cooling dynamoelectric machines whichachieves better cooling results than systems previously known andwithout their shortcomings and disadvantages. The advantageous resultsof this invention are achieved by spray coating the hot windings andsupporting structures with a finely atomized oil spray to provideintimate contact with the cooling medium. The cooling oil is atomizedunder hydrostatic pressure through hydraulic atomizing nozzles whichproject the finely divided particles of oil at low velocities. The lowvelocity of the oil impinging directly on the insulated windingsminimizes, if not eliminates, insulation erosion. The windage of theoil-misted air produced in the machine is so little as to be comparablein its deleterious effect to air windage.

Separate spray nozzles are provided for the stationary and for therotating windings to be cooled and means are provided for isolating eachof the relatively moving windings and supporting structures from thespray intended for the other. At the same time, steps are taken toprevent liquid oil coolant that coats the stationary and rotatingelements from flowing into the airgap.

The stationary windings are protected against direct impingement ofliquid oil flung centrifugally from the rotating elements. The oilcoating deposited by the spray on the stationary windings is collectedand pooled in direct heat-conducting relatioriship with the windingsand, particularly, areas of the windings that might not otherwise bereached with the atomized spray.

Finally, the introduction of oil directly into the machine and onto thewindings permits the elimination of troublesome contact seals. Forexample, oil is conducted from the supply passages in the stationarymachine housing to the center of the hollow shaft through a concentrictransfer tube having only a contactless journal bearing with the shaftand a self-aligning, nonrotating, no-slip O-ring seal with the housing.The journal bearing leaks a predetermined amount of oil which may beemployed advantageously to lubricate a bearing of the machine and/orcool auxiliary winding structures located nearby.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevation view of anAC generator embodying this invention;

FIG. 2 is a side elevation view sectioned axially through the machine ofFIGrl as indicated by the line 22; and

FIG. 3 is a transverse sectional view through the machine of FIGS. 1 and2 taken as indicated by the line 3-3 in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT The preferred embodiment describedbelow is a high-speed, brushless AC generator housed in a casing adaptedto interface with the'casing of a drive mechanism to form what is knownas an integrated drive generator. Typically, the drive mechanism is adevice which turns the generator at a constant speed, even when thedrive mechanism itself is driven by a variable speed power source. Theinvention is not limited to the particular dynamoelectric machinedescribed here nor to dynamoelectric machines integrally combined withdrive units. The invention comprehends, in its broadest aspect, allrotating dynamoelectric machines having heat-producing electricalwindings and including machines housed in their own complete cases. Insome of its more restricted aspects, it is especially applicable tobrushless dynamoelectric machines; i.e., machines having rectifierassemblies interconnecting rotating exciter output windings and rotatingmain field windings and all mounted on the rotor for rotation therewith.

As shown in FIG. 2, the generator comprises three alternators mounted ona common shaft 21 and all fitted and supported within a common casingindicated generally at 22. It will be observed that one end of casing 22is open for attachmentto a drive mechanism (not shown) to form anintegrated drive machine.

Shaft 21 is splined at its drive end 23 for driving connection with andsupport by the shaft of the driving mechanism. The antidrive end ofshaft 21 is supported for rotation by a bearing 24 removably mounted bysuitable means through an opening in the antidrive end of casing 22.This opening is closed by an end cap 25 whose further functions will bedescribed below.

The main alternator or output stage is located approximately in themiddle of the machine as shown in FIG. 2 and is, of course, the largestof the three alternators. The main alternator has an output winding 30located in the stator and wound upon the usual laminated annular corestructure 31. Output winding 30, in this embodiment, delivers athree-phase output to the main terminals of the machine T.

The rotor mounted on shaft 21 comprises a four-pole field winding 32supported on a conventional laminated four-pole rotor form 33. windingsare preferably formed of edge-wound rectangular wire as indicated inFIG. 2. As seen in FIG. 3, coil side braces 34 seal the span betweenpoles. The end turns of the field windings on each pole of the rotor aresupported by annular support rings 35.

The main alternator field winding is excited by direct current suppliedfrom a rotating rectifier assembly indicated generally at 40 (FIG. 2).The rectifier assembly 40 rectifies the alternating current output ofthe rotating output winding 41 of the main exciter mounted on shaft 21between drive end 23 and the main alternator. The stationary field 42 ofthe main exciter is of conventional salient pole construction supportedfrom casing 22 by a number of radial struts 43.

Field excitation for the main exciter is provided by a small pilotexciter machine located near the antidrive end of shaft 21 andcomprising a permanent magnet rotor 44 and stationary output winding 46supported in stator structure 47.

The rotating field and stationary output windings of the main alternatorproduce the greatest amount of heat and it is these windings or theircounterparts in other dynamoelectric machines which require the greatestamount of coolant.

Liquid coolant, such as a high-temperature oil compatible with theinsulation materials employed in building the machine and its windings,is supplied under pressure from the drive unit with which the generatorshown mates. In individual machines, the oil can be supplied from anysuitable source. A supply passage 50 is provided in housing 22 andextends generally axially from the face of housing mounting flange 51 tothe interface 52 of the housing and end cap 25. The supply passageopening 53 in mounting flange 51 is shown in FIG. 1. In the machineshown, cooling oil is supplied at a pressure of 270 p.s.i. and at a flowrate of 7.5 g.p.m. Supply passage 50 is tapped in the region of the mainalternator stator by a restrictor nozzle 54 which reduces the supplypressure to approximately 100 p.s.i. and delivers a metered coolant flowto a plurality of annular conduction cooling passages 55, machined incasing 22, and surrounding the back iron of the main alternator stator31. By suitable baffling, the inlet flow through restrictor nozzle 54 isdivided so that one-half flows one way around the stator and the otherhalf flows the other way. After wiping the outer diameter of the stator,the flow unites at an axially extending groove 56 for supplying annulardistributing manifolds or spray rings 57 located on opposite sides ofthe main alternator stator.

As shown in FIG. 2, spray rings 57 consist of annular members havingchannels closed by the interior surface of casing 22. O-ring seals 58prevent the escape of the oil coolant. Atomizing spray nozzles 60 aremounted at circumferentially spaced intervals in spray rings 57 and aredirected radially inwardly toward the backs or radially outer surfacesof the end turns of the main stator windings extending axially from eachannular end face 61 of the stator structure. As illustrated in FIGS. 1and 2, 24 atomizing spray nozzles 60 spray directly against the statorend turns.

Nozzles 60 are preferably hollow cone spray nozzles of conventionaldesign for finely atomizing the coolant oil supplied to them underhydrostatic pressure. The hydraulic atomization accomplished by thesenozzles produces a finely divided mist and projects it at lowvelocities. The result is a generally uniform and overall flowingcoating of liquid oil coolant on all surfaces including the end turnsthat are exposed to the nozzle spray. Despite the close proximity of thenozzles to the end turns, no deleterious erosion of the end turninsulation is experienced because of the low velocity and the finenessof the atomized particles of coolant.

The radially inner surfaces of the stator winding end turns are shieldedand supported by generally cylindrical shields 63 having a tight fitagainst the stator iron adjacent the main airgap 64 and extendingaxially out to and slightly beyond the end of the stator end turns wherethey terminate in a radially outwardly turned flange 65. The statorshields 63 collect and pool the flowing coolant that runs off the endturns, further directing the flow of cooling oil'over the end turns andto the drain area in the lower part of the machine. The stator shieldsguide the flow of oil over the end turns, causing it to wipe areas notexposed to the spray and, thus, eliminate potential hot spots. Further,the stator shields tend to prevent the flow of any oil supplied by thenozzles of the stator spray rings from flowing into the main airgap 64.Finally, stator spray shields protect the stator end turns fromcentrifugal impingement of oil introduced into the machine radiallyinwardly of them and also protect the insulated pans radially inwardlyof the stator from direct impingement of the stator spray.

The oil not bled off main supply passage 50 at stator restrictor nozzle54 continues on and down the castin channel in end cap 25. A channel 66in the end cap extends radially to the center of the machine and axiallyopposite the end of shaft 21. A transfer tube 67 sealed by an O-ring 68through a central port 69 in the face of end cap 25 extends into hollowshaft 21 where it has a controlled leakage noncontact journal seal 70.The O-ring joint in the end cap allows the transfer tube to beself-aligning. Preferably, the clearance between the shaft and thetransfer tube is controlled to permit approximately 0.05 g.p.m. ofcoolant oil to escape and to cool and lubricate bearing 24. The oil thatpasses through bearing 24 is pumped out by permanent magnet rotor 44 ofthe pilot exciter and splash cools its associated stator 47 and windings46.

The bulk of the coolant oil introduced into the machine enters thehollow rotor shaft 21 through transfer tube 67. Rotating distributingmanifolds or rotating spray rings 73 are mounted on shaft 21 adjacent toand associated with the opposite annular end faces 74 of the rotorstructure. Rotor spray rings 73 provide an annular passage surroundingthe hollow shaft 21 which is supplied with oil through restrictororifices 75 in the wall of the shaft. These orifices meter the flow andreduce the coolant pressure to approximately 100 p.s.i. In each rotatingspray ring 73 are mounted four spray nozzles 76 directed at the fourpoles of the rotor. Nozzles 76 are preferably full cone nozzles. Spraynozzles 76 which provide the cooling spray to the rotating fieldwindings 32 have no relative movement with respect to the windings sincethey are mounted on and rotate with the same shaft. The rotor spraynozzles are preferably aimed slightly below or radially inside the rotorwindings angled with respect to the axis of the shaft in the directionof rotation to compensate for centrifugal and circumferential dragforces imposed on the atomized spray during high-speed rotation of therotor. The outer surfaces of the rotor end turns 32 are cooled by thedirect impingement of the coolant spray from nozzles 76. The innersurfaces of end turns 32 are cooled by a centrifugal flow of oil overthem. It should be noted that the edge-wound rectangular wire end turnsin section as shown in FIG. 2 comprise a wall of copper axially spacedfrom the laminated pole core structure 33. The radially outer end of thewall supported by the annular supporting rings 35 and the radially innerend is spaced from the rotor shaft, permitting oil from rotor spraynozzles 76 to be directed into the spaces behind the rotor winding endturns. After cooling the outer surface of the rotor end turns, theflowing coating of oil is centrifuged onto stator shields 63 which guideit to the antidrive drain area in the lower part of the machine. Thecooling surface flow on the inner side of the rotor winding end turnsleaves the rotor at the urging of centrifugal force through rotor oilrelief holes 79. Between the drive end and the antidrive end rotor sprayrings, the hollow shaft is preferably provided with an aluminum insert80 having axial conduction cooling passages 81 machined in its outersurface for channeling the flow of oil coolant against the inside wallof the rotor shaft. The rotor conduction passages are designed forlaminar flow and are shaped for optimum transfer of heat from the rotoriron.

Rotor spray nozzles 76, like stator spray nonles 60, finely atomize thecooling oil sprayed to them under hydrostatic pressure and project it atlow velocity for uniform, overall deposition on the exposed surfaces ofthe rotor winding end turns. The fine atomization achieved by thenozzles and the low velocity at which the atomized coolant is projectedminimizes any deleterious erosion of the insulation by the spray.

The main exciterrotor is provided with a support 82 having an annularaxially extending flange 83. Mounted within the flange, as shown in FIG.1, are six rectifiers 84 circumferentially spaced and arranged generallyin a plane normal to their axis of rotation. The anode and cathode ofeach rectifier 84 is radially aligned with respect to the rotation axis.One set of three adjacent rectifiers 84 is mounted on a commonconducting and cooling strip 85 and the other set of three adjacentrectifiers 84 is mounted on another electrically isolated cooling andconducting strip 86. Heat sink conducting strips 85 and 86 are mountedon exciter rotor support 82 by means of tabs 87 and screws 88. Strips 89of insulating material electrically insulate the heat sinks from rotorsupport 82.

Hollow shaft 21 is provided with two orifices 90 through the shaft walland which permit approximately 0.5 g.p.m. of the remaining coolant flowthrough the shaft to bathe and cool the rectifiers. The oil meteredthrough these orifices is collected in an annular channel having aradially inwardly facing open side and formed by rotor support 82 andits flange 83 and an annular reservoir dam 91. Thus, the rotatingrectifiers 84 and their heat sinks 85 and 86 stand in reservoir oil heldin place with the annular channel by centrifugal force. The oil from thereservoir overflows through openings 92 in support 82 and tends to coolthe main exciter rotor by wiping the inner diameter of the exciter rotorsupport 82 and the antidrive end turn of the exciter rotor windings 41.

The remainder of the coolant flow is transferred to the hollow shaft ofthe drive machine.

The oil which collects in the lower side at the antidrive end of thegenerator is scavenged by a drain pump in the drive mechanism through anoil drain port 95 in the antidrive end of the casing. The oil whichcollects at the drive end of the generator housing is scavenged byanother drain pump in the drive mechanism through a similar port. Thecareful attention to scavenging of the oil introduced through thismethod of spray oil cooling tends to eliminate any deleterious churninglosses that would offset the advantages otherwise afforded by themethod.

Each of the various cooling oil deposition and coating means may beemployed without all of the others as shown in the preferred embodimentherein. ln a machine without a rotating rectifier assembly, for example,the centrifugal reservoir can be eliminated. The heavy cooling loadssuch as those consisting of the main field and output windings are mosteffectively handled by flowing coatings of coolant continuously andgenerally uniformly deposited on as many of their surfaces as possiblefrom atomizing nozzles providing a finely divided spray of coolant. Onthe other hand, the centrifugal reservoir mode of direct coolantapplication to the structures to be cooled is effective in the case ofthe rotating rectifier assembly. Both the atomized spray technique andthe reservoir provide a flowing coating of coolant over and directly onthe structures and/or windings to be cooled. This invention comprehendsapplying a flowing coating of coolant to rotating or stationaryrectifiers by means of an atomized coolant spray as well as toelectrical windings and core structures by submerging them in areservoir provided with coolant flow through it.

Various other modifications and adaptations of the method and meansdescribed above and comprehended by this invention will readily occur tothose skilled in the art to which this invention pertains and may bemade without departing from the spirit and scope of the invention.

Iclaim:

1. In a dynamoelectric machine having a housing, cylindrical stator withannular end faces and including a core structure supportingheat-producing electrical windings having end turns adjacent the annularend faces, and a rotor with annular end faces and mounted on a shaft forrotation within said stator and including a core structure supportingheat-producing electrical windings having end turns adjacent the annularend faces, the improved means for removing heat from said windings andcore structures during operation of the machine comprising a circulararray of atomizing devices supported adjacent to and associated in fixedrelationship with each annular end face of said stator structure, saidatomizing devices being adapted to atomize liquid supplied to them underhydrostatic pressure and to project the atomized particles in adiverging spray pattern and in a direction generally radially inwardlyof the machine and at the end turns of said stator windings,

a plurality of atomizing devices supported on the shaft of the machineadjacent to each annular end face of and for rotation with said rotorstructure, said atomizing devices being adapted to atomize liquidsupplied to them under hydrostatic pressure and to project the atomizedparticles in a diverging spray pattern and in a direction generallytoward the annular end faces of said rotor and the end turns of saidrotor windings,

means for supplying liquid coolant to said atomizing devices underhydrostatic pressure,

whereby atomized liquid coolant is continuously deposited on theelectrical windings end turns providing a flowing coating of coolantover and off of them to pick up and carry away heat from them.

2. The improved means of claim 1 in which said means for supplyingliquid coolant under hydrostatic pressure to said atomizing devicesdirected at the stator comprises a supply passage in the housingextending to both stator end faces and connected to a source of liquidcoolant under hydrostatic pressure, a circular distribution manifoldmounted adjacent each annular end face of said stator for supportingsaid atomizing devices associated with the stator annular end faces andsupplying liquid coolant thereto, said manifolds each having an internalpassage in communication with the housing supply passage and theatomizing devices mounted on the manifolds.

3. The improved means of claim 1 in which said means for supplyingliquid coolant under hydrostatic pressure to said atomizing devicesdirected at the rotor comprises a supply passage extending axiallythrough the shaft of the machine connected to a source of liquid coolantunder hydrostatic pressure and a distribution manifold mounted on andencircling the shaft adjacent each annular end face of said rotor forsupporting said atomizing devices and supplying liquid coolant thereto,said manifolds each having an internal passage in communication with thesupply passage internal to the shaft and with the atomizing devices onthe manifolds.

4. The improved means of claim 1 in which said means for supplyingliquid coolant under hydrostatic pressure to said atomizing devicesdirected at the stator and rotor windings comprises a first supplypassage in the housing extending to both stator end faces and to thecenter of one end of the machine, and

distribution passages in communication with said housing supply passageand the atomizing devices directed at the stator,

a second supply passage extending axially through the shaft of themachine,

distribution passages in communication with said shaft supply passageand the atomizing devices supported on the shaft and directed at therotor windings, and

conduit means for connecting said housing and shaft supply passages toprovide a continuous coolant supply path through the machine.

5. The improved means of claim 4 in which said conduit means connectingsaid housing and shaft supply passages comprises a transfer tubeextending axially from and concentric with said shaft supply passage andbeyond the end of said shaft into sealed connection with said housingsupply passage, said tube having a journal seal with said shaft topermit relative rotation of said shaft with respect to said tube whileconducting coolant, said journal seal having a predetermined clearanceto provide a coolant-distributing passage.

6. The apparatus of claim 1 in which said atomizing devices mounted onsaid shaft for rotation with the rotor are directed radially below andcircumferentially in the direction of rotation of the rotor with respectto the central portion of the structure and windings they are intendedto spray.

7. The apparatus of claim 1 in which the stator winding has end turnsextending axially of the machine beyond and away from each annular endface and said atomizing devices associated with the stator are directedat the radially outer surfaces of the winding end turns for directimpingement thereon of the atomized spray of said atomizing devices, andtogether with substantially cylindrical coolant spray shields extendingaxially of the machine from each stator end face radially inside theadjacent end turns and terminating in an outwardly turned radial flangebeyond the axial extent of the adjacent end turns for shielding thestator including its windings from direct impingement thereon ofatomized spray from the rotor atomizing device and the rotor includingits windings from direct impingement thereon of atomized spray from thestator atomizing devices and for collecting and pooling the coolantsprayed at the stator end turns about them.

8. In a dynamoelectric machine having a housing, a rotor with annularend faces and mountedon a shaft for rotation within said stator andincluding a core structure supporting heat-producing electrical windingshaving end turns adjacent the annular end faces, the improved means forremoving heat from said windings and core structures during operation ofthe machine comprising a plurality of atomizing devices supported on theshaft of the machine adjacent to each annular end face of and forrotation with said rotor structure, said atomizing devices being adaptedto atomize liquid supplied to them under hydrostatic pressure and toproject the atomized particles in a diverging spray pattern and in adirection generally toward the annular end faces of said rotor and theend turns of said rotor windings, and particularly radially below andcircumferentially in the direction of rotation of the rotor with respectto the central portion of the structure and windings they are intendedto spray,

means for supplying liquid coolant to said atomizing devices underhydrostatic pressure,

whereby atomized liquid coolant is continuously deposited on theelectrical windings end turns providing a flowing coating of coolantover and off of them to pick up and carry away heat from them.

9. In a dynamoelectric machine having a housing, cylindri cal statorwith annular end faces and including a core structure supportingheat-producing electrical windings having end turns adjacent the annularend faces, the improved means for removing heat from said windings andcore structures during operation of the machine comprising a circulararray of atomizing devices supported adjacent to and associated in fixedrelationship with each annular end face of said stator structure, saidatomizing devices being adapted to atomize liquid supplied to them underhydrostatic pressure and to project the atomized particles in adiverging spray pattern and in a direction generally radially inwardlyof the machine and at the end turns of said stator windings,

a supply passage in the housing extending to both stator end faces,

a circular distribution manifold mounted adjacent each annular end faceof said stator for supporting said atomizing devices associated with thestator annular end faces and supplying liquid coolant thereto, saidmanifolds each having an internal passage in communication with thehousing supply passage and the atomizing devices mounted on themanifolds,

means for supplying liquid coolant under hydrostatic pressure to saidhousing s u ply assage, whereby atomized liqui coo ant lS continuouslydeposited on the electrical windings end turns providing a' flowingcoating of coolant over and off of them to pick up and carry away heatfrom them.

10. In a dynamoelectric machine having a housing, a shaft mounted forrotation therein and a rotating assembly of electrical conductingelements mounted on the shaft for rotation therewith, the improved meansfor removing heat from the electrical elements of the assembly duringoperation of the machine comprising an annular channel having a radiallyinwardly facing open side mounted on said shaft for rotation with it andin which said electrical elements are circumferentially arranged andmounted,

a coolant passage in said shaft having orifices for metering a flow ofcoolant under hydrostatic pressure from the shaft into said annularchannel during rotation of the shaft and channel, and

overflow openings in said channel to meter a flow of coolant out of saidchannel whereby said electrical elements are cooled in a centrifugallymaintained reservoir of coolant having a flow of coolant therethrough.

11. The improved means of claim 10 in which said electrical conductingelements are rectifiers.

12. The improved means of claim 10 together with other electricalconducting elements and their supporting structures mounted for rotationwith said annular channel and radially outwardly of the overflowopenings in the channel whereby the overflow of the coolant from thechannel provides a flowing coating of coolant directly of said otherelectrical conducting elements and their supporting structures.

2. The improved means of claim 1 in which said means for supplyingliquid coolant under hydrostatic pressure to said atomizing devicesdirected at the stator comprises a supply passage in the housingextending to both stator end faces and connected to a source of liquidcoolant under hydrostatic pressure, a circular distribution manifoldmounted adjacent each annular end face of said stator for supportingsaid atomizing devices associated with the stator annular end fAces andsupplying liquid coolant thereto, said manifolds each having an internalpassage in communication with the housing supply passage and theatomizing devices mounted on the manifolds.
 3. The improved means ofclaim 1 in which said means for supplying liquid coolant underhydrostatic pressure to said atomizing devices directed at the rotorcomprises a supply passage extending axially through the shaft of themachine connected to a source of liquid coolant under hydrostaticpressure and a distribution manifold mounted on and encircling the shaftadjacent each annular end face of said rotor for supporting saidatomizing devices and supplying liquid coolant thereto, said manifoldseach having an internal passage in communication with the supply passageinternal to the shaft and with the atomizing devices on the manifolds.4. The improved means of claim 1 in which said means for supplyingliquid coolant under hydrostatic pressure to said atomizing devicesdirected at the stator and rotor windings comprises a first supplypassage in the housing extending to both stator end faces and to thecenter of one end of the machine, and distribution passages incommunication with said housing supply passage and the atomizing devicesdirected at the stator, a second supply passage extending axiallythrough the shaft of the machine, distribution passages in communicationwith said shaft supply passage and the atomizing devices supported onthe shaft and directed at the rotor windings, and conduit means forconnecting said housing and shaft supply passages to provide acontinuous coolant supply path through the machine.
 5. The improvedmeans of claim 4 in which said conduit means connecting said housing andshaft supply passages comprises a transfer tube extending axially fromand concentric with said shaft supply passage and beyond the end of saidshaft into sealed connection with said housing supply passage, said tubehaving a journal seal with said shaft to permit relative rotation ofsaid shaft with respect to said tube while conducting coolant, saidjournal seal having a predetermined clearance to provide acoolant-distributing passage.
 6. The apparatus of claim 1 in which saidatomizing devices mounted on said shaft for rotation with the rotor aredirected radially below and circumferentially in the direction ofrotation of the rotor with respect to the central portion of thestructure and windings they are intended to spray.
 7. The apparatus ofclaim 1 in which the stator winding has end turns extending axially ofthe machine beyond and away from each annular end face and saidatomizing devices associated with the stator are directed at theradially outer surfaces of the winding end turns for direct impingementthereon of the atomized spray of said atomizing devices, and togetherwith substantially cylindrical coolant spray shields extending axiallyof the machine from each stator end face radially inside the adjacentend turns and terminating in an outwardly turned radial flange beyondthe axial extent of the adjacent end turns for shielding the statorincluding its windings from direct impingement thereon of atomized sprayfrom the rotor atomizing device and the rotor including its windingsfrom direct impingement thereon of atomized spray from the statoratomizing devices and for collecting and pooling the coolant sprayed atthe stator end turns about them.
 8. In a dynamoelectric machine having ahousing, a rotor with annular end faces and mounted on a shaft forrotation within said stator and including a core structure supportingheat-producing electrical windings having end turns adjacent the annularend faces, the improved means for removing heat from said windings andcore structures during operation of the machine comprising a pluralityof atomizing devices supported on the shaft of the machine adjacent toeach annular end face of and for rotation with said rotor structure,said atomizing devices being adapted to atomize liqUid supplied to themunder hydrostatic pressure and to project the atomized particles in adiverging spray pattern and in a direction generally toward the annularend faces of said rotor and the end turns of said rotor windings, andparticularly radially below and circumferentially in the direction ofrotation of the rotor with respect to the central portion of thestructure and windings they are intended to spray, means for supplyingliquid coolant to said atomizing devices under hydrostatic pressure,whereby atomized liquid coolant is continuously deposited on theelectrical windings end turns providing a flowing coating of coolantover and off of them to pick up and carry away heat from them.
 9. In adynamoelectric machine having a housing, cylindrical stator with annularend faces and including a core structure supporting heat-producingelectrical windings having end turns adjacent the annular end faces, theimproved means for removing heat from said windings and core structuresduring operation of the machine comprising a circular array of atomizingdevices supported adjacent to and associated in fixed relationship witheach annular end face of said stator structure, said atomizing devicesbeing adapted to atomize liquid supplied to them under hydrostaticpressure and to project the atomized particles in a diverging spraypattern and in a direction generally radially inwardly of the machineand at the end turns of said stator windings, a supply passage in thehousing extending to both stator end faces, a circular distributionmanifold mounted adjacent each annular end face of said stator forsupporting said atomizing devices associated with the stator annular endfaces and supplying liquid coolant thereto, said manifolds each havingan internal passage in communication with the housing supply passage andthe atomizing devices mounted on the manifolds, means for supplyingliquid coolant under hydrostatic pressure to said housing supplypassage, whereby atomized liquid coolant is continuously deposited onthe electrical windings end turns providing a flowing coating of coolantover and off of them to pick up and carry away heat from them.
 10. In adynamoelectric machine having a housing, a shaft mounted for rotationtherein and a rotating assembly of electrical conducting elementsmounted on the shaft for rotation therewith, the improved means forremoving heat from the electrical elements of the assembly duringoperation of the machine comprising an annular channel having a radiallyinwardly facing open side mounted on said shaft for rotation with it andin which said electrical elements are circumferentially arranged andmounted, a coolant passage in said shaft having orifices for metering aflow of coolant under hydrostatic pressure from the shaft into saidannular channel during rotation of the shaft and channel, and overflowopenings in said channel to meter a flow of coolant out of said channelwhereby said electrical elements are cooled in a centrifugallymaintained reservoir of coolant having a flow of coolant therethrough.11. The improved means of claim 10 in which said electrical conductingelements are rectifiers.
 12. The improved means of claim 10 togetherwith other electrical conducting elements and their supportingstructures mounted for rotation with said annular channel and radiallyoutwardly of the overflow openings in the channel whereby the overflowof the coolant from the channel provides a flowing coating of coolantdirectly of said other electrical conducting elements and theirsupporting structures.